Intelligent oil pumping unit attitude control method capable of running at variable speed in multiple time periods

Abstract

The invention discloses a posture control method for an intelligent oil pumping unit capable of running at variable speed in multiple time periods. According to the method, the operation duration of a single stroke frequency of the oil pumping unit is set, the operation path of each stroke frequency of the oil pumping unit is divided into multiple sections of segmented paths, and the distance of each segmented path and the operation mode and the operation duration of a horse head of the oil pumping unit in each segmented path are set; enabling the pumping unit to start working according to the calculated initial values of the initial speed, the end speed and the acceleration of the horsehead in each section of the segmented path, and then adjusting the initial speed, the end speed and the acceleration of the horsehead in each section of the segmented path according to the measured actual running time of a single stroke frequency of the pumping unit; the absolute error value between the total operation duration of the preset single stroke frequency and the actual total operation duration of the single stroke frequency of the oil pumping unit does not exceed a preset value. The pumping unit can normally operate under the working condition of a low-yield oil well, invalid stroke frequency and stroke loss can be reduced, efficiency is improved, and electric charge and maintenance cost generated by operation of the pumping unit are reduced.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of oilfield machine well production, and particularly relates to a posture control method of an intelligent oil pumping unit running at variable speed in multiple time periods. BACKGROUND

[0002] At present, there are about 200,000 low-yield oil wells in China, but most of the existing oil pumping units for oil fields work in a power frequency operation mode. When the reciprocating motion reaches the upper dead point and the lower dead point, the speed will change abruptly (usually the speed is kept constant, and the direction of the speed is changed), which will produce inertia effect and further cause alternating load, so that the oil pumping unit tubing and sucker rod are prone to eccentric wear, the service life of the oil pumping unit tubing and sucker rod is reduced, the pump inspection period is reduced, the downtime for maintenance is lengthened, the maintenance cost is increased, and moreover, this also leads to the fact that the average speed of the existing oil pumping unit for oil fields near the lower dead point position is still relatively high, the residence time at the lower dead point position is short, and moreover, the running stroke is not corrected, so that when the error accumulates, the actual speed near the lower dead point position will deviate greatly from the designed speed, and when the liquid supply is insufficient, the "empty pumping" or "half empty pumping" phenomenon is prone to occur, which increases the stroke loss and invalid stroke, and when the oil production needs to be increased, the stroke frequency has to be increased, so that the system efficiency is generally low, and the low-yield oil well cannot be well adapted to the liquid supply speed. Because of the "empty pumping" or "half empty pumping" phenomenon, the oil pumping amount is small, and the economic value generated cannot offset the electricity cost and maintenance cost generated by the operation of the oil pumping unit, so that the exploitation value of the low-yield oil well is low. SUMMARY

[0003] The present application aims at overcoming the deficiencies of the prior art, and provides a posture control method of an intelligent oil pumping unit running at variable speed in multiple time periods.

[0004] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0005] The posture control method of the intelligent oil pumping unit running at variable speed in multiple time periods comprises the following steps:

[0006] Step one: the distance from the upper dead point to the lower dead point of the horse head of the oil pumping unit is S, the running path of each stroke of the oil pumping unit is divided into multiple segment paths, the distance of each segment path is set, the running mode of the horse head in each segment path is set, the running time of each stroke of the oil pumping unit is T, the running speed of the horse head at the upper dead point position and the lower dead point position is 0, and the running time of the horse head in each segment path is set.

[0007] Step two: the initial speed, the end speed and the acceleration initial value of the horse head in each segment path are calculated.

[0008] Step 3: The pumping unit head operates at the starting speed, ending speed, and acceleration of each segment path, and the actual running time T of each pumping stroke is detected using proximity switches installed on the pumping unit body. 实 .

[0009] Step 4: Calculate the actual operating time T of each pumping unit stroke obtained through testing. 实 If the absolute error value of the running time T of each stroke of the pumping unit is greater than the preset value, the starting speed, ending speed and acceleration of the donkey head in each segment path are corrected, and then the process returns to step three. Otherwise, the donkey head continues to work with the current starting speed, ending speed and acceleration of the donkey head in each segment path.

[0010] Preferably, the operating path of each stroke of the pumping unit is divided into 10 segments. The donkey head operates in a uniform acceleration mode in the first, second, sixth, and seventh segments, in a uniform deceleration mode in the fourth, fifth, ninth, and tenth segments, and in a uniform speed mode in the third and eighth segments.

[0011] More preferably, the running time of the donkey head in each segment path is

[0012] t i =α i T

[0013] In the formula, t i α represents the running time of the donkey head in the i-th segment of the path. i This represents the running time coefficient of the donkey head in the i-th segment of the path, where i = 1, 2, 3, ..., 10, and t1 + t2 + t3 + t4 + t5 = t6 + t7 + t8 + t9 + t 10 =T / 2.

[0014] More preferably, t1 = t5 = t6 = t 10 , t2=t4=t7=t9, t3=t8.

[0015] More preferably, the initial values ​​of the donkey's head's starting speed, ending speed, and acceleration in each segment of the path are calculated using the following formula:

[0016]

[0017] In the formula, S i Let S1+S2+S3+S4+S5=S6+S7+S8+S9+S 10 =S; Let V be the average speed of the donkey's head on the i-th segment of the path.ia Vi is the initial speed of the horse head at the i-th segment of the segmented path ib ai is the final speed of the horse head at the i-th segment of the segmented path i ai is the acceleration of the horse head at the i-th segment of the segmented path

[0018] wherein the initial speed of the horse head at each segment of the segmented path except the first segment is equal to the final speed of the horse head at the previous segment, and the speed of the horse head at the top dead center position and the bottom dead center position is 0, i.e. Vi 1a = V 5b = V 6a = V 10b = 0, and the initial values of the initial speed, the final speed and the acceleration of the horse head at each segment of the segmented path are obtained by calculation.

[0019] More preferably, the real-time speed of the horse head at each segment of the segmented path is

[0020] Vi ij = V ia + a i · t ij

[0021] wherein t ij is the j-th time point during the running of the horse head at the i-th segment of the segmented path, and V ij is the running speed of the horse head at t ij .

[0022] Preferably, the process of correcting the initial speed, the final speed and the acceleration of the horse head at each segment of the segmented path is as follows: when T 实 > T, the initial speed of the horse head at each segment of the segmented path is increased to a times the initial speed of the horse head at the corresponding segment calculated last time, and a > 1; and when T 实 < T, the initial speed of the horse head at each segment of the segmented path is decreased to b times the initial speed of the horse head at the corresponding segment calculated last time, and b < 1.

[0023] The present application has the following advantages:

[0024] 1、The present application can make the pumping unit run normally under the condition of low-yield oil well, and can reduce the stroke loss and invalid stroke, improve the system efficiency, and reduce the electricity and maintenance cost generated by the operation of the pumping unit. Specifically, the present application divides the running path of each stroke of the pumping unit into multiple segmented paths, so that the horse head moves at variable speed in a single stroke, and the actual running time of the single stroke of the pumping unit is measured. If the absolute error value between the preset running time of the single stroke and the actual running time of the single stroke of the pumping unit exceeds the preset value, the initial speed, the final speed and the acceleration of the horse head in each segmented path are corrected, so that the pumping unit can be corrected after each running stroke, and the stroke loss is reduced. Further, by setting the horse head to move at variable speed in a single stroke, and setting the speed of the horse head at the top dead center position and the bottom dead center position to be 0, the phenomenon of the horse head running ahead of the piston of the pumping unit can be eliminated, the compression load generated when the sucker rod of the pumping unit rises to the top dead center position can be eliminated, the bending of the sucker rod can be reduced, the wear of the sucker rod and the oil pipe can be reduced, the tensile load generated when the sucker rod descends to the bottom dead center position can be eliminated, and the alternating load suffered by the sucker rod during reciprocating motion can be eliminated, the eccentric wear of the sucker rod and the oil pipe can be reduced, the service life of the sucker rod and the oil pipe can be increased, the pump inspection period can be prolonged, the downtime for maintenance can be reduced, the maintenance cost can be reduced, and the residence time of the piston of the pumping unit near the top dead center and the bottom dead center can be increased, so that the liquid lifting capacity of a single stroke of the pumping unit can be increased, and the invalid stroke and the stroke loss can be reduced, and the pump efficiency can be improved. Therefore, the present application can make the pumping unit run normally at low stroke (0.5-2 times / min) in a segmented variable speed motion mode, and even when the pumping unit runs at low stroke, the oil production capacity is higher than that of the existing pumping unit running at high stroke, and the pumping unit can better adapt to the condition of low-yield oil well.

[0025] 2、The present application can obtain the real-time running speed of the horse head of the pumping unit through real-time calculation, and solves the problem that the existing pumping unit needs to be equipped with a motor rotary transformer to detect the real-time running speed of the horse head, which needs to damage the structure of the driving motor of the pumping unit and takes a long time to install. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The present application is a schematic diagram of the running speed and trajectory curve of the horse head in a single stroke. DETAILED DESCRIPTION

[0027] The present application will be further described below in conjunction with the drawings.

[0028] The present application is a smart pumping unit posture control method running at multiple time periods and variable speeds, which is as follows:

[0029] Step one, as Figure 1As shown, the distance from the top dead center to the bottom dead center of the pumping unit horse head is S, the running path of the pumping unit in each stroke is divided into 10 segment paths, and the distance of each segment path is set; the running mode of the pumping unit horse head in each segment path is set, the running time of the pumping unit in each stroke (including the upstroke and the downstroke, i.e. the process that the pumping unit horse head moves from the bottom dead center to the top dead center and then returns to the bottom dead center) is set as T, and the running speed of the horse head at the top dead center position and the bottom dead center position is set as 0, and the running time of the horse head in each segment path is set. Among them, the running mode of the horse head in the first segment path, the second segment path, the sixth segment path and the seventh segment path is uniform acceleration, the running mode in the fourth segment path, the fifth segment path, the ninth segment path and the tenth segment path is uniform deceleration, and the running mode in the third segment path and the eighth segment path is uniform speed; the distance of the ith segment path is S i , and i = 1, 2, 3, …, 10, S1+S2+S3+S4+S5=S6+S7+S8+S9+S 10 = S; the running time of the horse head in each segment path is

[0030] t i = α i T

[0031] In the formula, t i represents the running time of the horse head in the ith segment path, α i represents the running time coefficient of the horse head in the ith segment path, and t1+t2+t3+t4+t5=t6+t7+t8+t9+t 10 =T / 2, in the embodiment, S1=S2=…=S 10 =0.2S, t1=t5=t6=t 10 =0.095T, t2=t4=t7=t9=0.12T, t3=t8=0.07T.

[0032] Step two, according to the distance of each segment path set in step one, the running time and running mode of the horse head in each segment path, and the running speed of the horse head at the top dead center position and the bottom dead center position, the initial speed, the end speed and the acceleration initial value of the horse head in each segment path are calculated. Among them, the calculation formula of the initial speed, the end speed and the acceleration initial value of the horse head in each segment path is

[0033]

[0034] In the formula, V is the average speed of the horse head in the ith segment path, V ia is the initial speed of the horse head in the ith segment path, V ib is the end speed of the horse head in the ith segment path, and ai the acceleration of the horse head in the ith segment of the segmented path;

[0035] wherein the initial speed of the horse head in each segment of the segmented path except the first segment is equal to the final speed of the horse head in the previous segment, and the speed of the horse head at the top dead center position and the bottom dead center position is 0, i.e. V 1a = V 5b = V 6a = V 10b = 0, and the initial speed, the final speed and the acceleration of the horse head in each segment of the segmented path are calculated. Figure 1 The running speed curve shown in the figure only represents the speed value, and does not involve the speed direction.

[0036] Step three, the horse head works at the initial speed, the final speed and the acceleration of each segment of the segmented path, and the actual running time T of each stroke of the pumping unit is detected by the proximity switch installed on the pumping unit body. 实 .

[0037] Step four, the absolute error value |T 实 of the actual running time T of each stroke of the pumping unit detected and the set running time T of each stroke of the pumping unit is calculated. 实 If |T 实 > 0.1s, the initial speed, the final speed and the acceleration of the horse head in each segment of the segmented path are corrected, and then the horse head works at the corrected initial speed, the final speed and the acceleration of each segment of the segmented path, if |T 实 ≤ 0.1s, the horse head continues to work at the current initial speed, the final speed and the acceleration of each segment of the segmented path, and the real-time speed of the horse head in each segment of the segmented path is

[0038] V ij = V ia + a i · t ij

[0039] In the formula, t ij is the jth time point in the running process of the horse head in the ith segment of the segmented path, and V ij is the running speed of the horse head at the jth time point in the running process of the horse head in the ith segment of the segmented path.

[0040] wherein the process of correcting the initial speed, the final speed and the acceleration of the horse head in each segment of the segmented path is as follows: when T 实 > T, the initial speed of the horse head in each segment of the segmented path is increased to 1.05 times of the initial speed of the horse head in the corresponding segment calculated last time, and when T 实

Claims

1. A method for attitude control of an intelligent pumping unit operating at variable speeds over multiple time periods, characterized in that: Step 1: Let the distance between the top dead center and the bottom dead center of the pumping unit be S. Divide the running path of each stroke of the pumping unit into multiple segments. Set the distance of each segment and the running mode of the pumping unit's head in each segment. Let the running time of each stroke of the pumping unit be T. The running speed of the head at the top dead center and the bottom dead center is 0. Also, set the running time of the head in each segment. Step 2: Calculate the initial velocity, final velocity, and initial acceleration of the donkey head on each segment of the path; Step 3: The pumping unit head operates at the starting speed, ending speed, and acceleration of each segment path, and the actual running time T of each pumping stroke is detected using proximity switches installed on the pumping unit body. 实 ; Step 4: Calculate the actual operating time T of each pumping unit stroke obtained through testing. 实 If the absolute error value of the running time T of each stroke of the pumping unit is greater than the preset value, the starting speed, ending speed and acceleration of the donkey head in each segment path are corrected, and then the process returns to step three. Otherwise, the donkey head continues to work with the current starting speed, ending speed and acceleration of the donkey head in each segment path.

2. The intelligent oil pumping unit attitude control method for multi-time-segment variable speed operation according to claim 1, characterized in that: The operating path of each stroke of the pumping unit is divided into 10 segments. The donkey head operates in the first, second, sixth, and seventh segments with uniform acceleration, in the fourth, fifth, ninth, and tenth segments with uniform deceleration, and in the third and eighth segments with uniform speed.

3. The intelligent oil pumping unit attitude control method for multi-time-segment variable speed operation according to claim 2, characterized in that: The running time of the donkey head in each segment path is: t i =α i T In the formula, t i α represents the running time of the donkey head in the i-th segment of the path. i This represents the running time coefficient of the donkey head in the i-th segment of the path, where i = 1, 2, 3, ..., 10, and t1 + t2 + t3 + t4 + t5 = t6 + t7 + t8 + t9 + t 10 =T / 2.

4. The intelligent oil pumping unit attitude control method for multi-time-segment variable speed operation according to claim 3, characterized in that: t1=t5=t6=t 10 t2=t4=t7=t9,t3=t8。 5. The intelligent oil pumping unit attitude control method for multi-time-segment variable speed operation according to claim 3, characterized in that: The formulas for calculating the initial values ​​of the donkey's starting speed, ending speed, and acceleration in each segment of the path are as follows: In the formula, S i Let S1+S2+S3+S4+S5=S6+S7+S8+S9+S 10 =S; Let V be the average speed of the donkey's head on the i-th segment of the path. ia Let V be the initial velocity of the donkey's head in the i-th segment of the path. ib Let a be the final speed of the donkey's head in the i-th segment of the path. i Let be the acceleration of the donkey's head in the i-th segment of the path; In this scenario, the donkey's initial speed in each segment of the path, excluding the first segment, is equal to its ending speed in the previous segment. Furthermore, the donkey's speed at the top and bottom endpoints is zero, i.e., V. 1a =V 5b =V 6a =V 10b =0, and then the initial speed, ending speed and initial acceleration of the donkey head in each segment path are obtained by calculation.

6. The intelligent oil pumping unit attitude control method for multi-time-segment variable speed operation according to claim 5, characterized in that: The real-time speed of the donkey's head on each segmented path is V. ij =V ia +a i ·t ij In the formula, t ij Let V be the j-th time point during the i-th segmented path journey of the donkey head. ij For the donkey's head at t ij The running speed at that time.

7. A method for attitude control of an intelligent pumping unit operating with variable speed in multiple time periods according to any one of claims 1 to 6, characterized in that: The process of correcting the starting speed, ending speed, and acceleration of the donkey head in each segmented path is as follows: When T 实 > T, the starting speed of the donkey head in each segmented path is increased to α times the starting speed of the donkey head in the corresponding segmented path calculated last time, and α > 1. When T 实 < T, the starting speed of the donkey head in each segmented path is decreased to β times the starting speed of the donkey head in the corresponding segmented path calculated last time, and β < 1.

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